Attempts to answer difficult questions about battle tactics employed by the United States Army Weapons improved rapidly after the Civil War, raising difficult questions about the battle tactics employed by the United States Army. The most fundamental problem was the dominance of the tactical defensive, when defenders protected by fieldworks could deliver deadly fire from rifles and artillery against attackers advancing in close-ordered lines. The vulnerability of these offensive forces as they crossed the so-called "deadly ground" in front of defensive positions was even greater with the improvement of armaments after the Civil War.